The present invention relates to a method of making a medical electrode and, more particularly, to a method of making a disposable electrosurgical patient electrode which includes a layer of cured, electrically conductive hydrogel material.
In various types of medical procedures, it is necessary to establish good electrical contact with the skin of a patient. During electrosurgical procedures, for example, an electrosurgical generator produces a high frequency electric current which is supplied an active electrode. The active electrode is used by the surgeon to cut tissue, and to coagulate blood vessels, and the like. To provide a return path for the electrosurgical current to the generator, an indifferent, or patient, electrode is placed in contact with the skin of the patient and connected by a lead to the return terminal of the generator. By maintaining a large area in contact with the electrode, the current density is held to a sufficiently low level to avoid damage to the skin at the indifferent electrode attachment site.
Various types of electrodes have been utilized in the past. Disposable, single-use electrodes have become increasingly popular for electrosurgical procedures. Such electrodes are shown, for example, in U.S. Pat. No. 3,848,600, issued Nov. 19, 1974, to Patrick et al and U.S. Pat. No. 3,601,126, issued Aug. 24, 1971, to Estes. The Patrick et al patent discloses an indifferent electrode which includes a sponge pad which is soaked with an electrode jelly material. Similarly, the Estes patent discloses a porour sheet of spongy material which is soaked with a viscous saline solution. Although providing good electrical contact with a patient's skin, disposable electrodes, carrying a pad soaked with an electrolyte paste, are somewhat messy and require that the application site be subsequently cleaned. Additionally, some types of electrolyte paste may tend to dry out if improperly stored, resulting in a loss in conductivity.
Medical electrodes for use as diagnostic electrodes and as surgical electrodes have been developed using various hydrogel materials. Such a hydrogel material is a three dimensional network of hydrophillic polymer material, which is generally covalently or ionically cross-linked and which contains a high level of water. Hydrogel materials are advantageous in that they can be made to be tacky, providing good adhesion to and electrical contact with, a patient's skin, while at the same time being sufficiently cohesive such that a residue of hydrogel material is not left on the skin of a patient when the electrode is removed and discarded. Due to the nature of such hydrogel materials, however, they have previously been difficult to handle in the electrode manufacturing process.
Accordingly, there is a need for an improved method of making a medical electrode for providing electrical contact with the skin of patient, which includes a quantity of cured hydrogel material.